In the realm of picture-making, certain rules have emerged over time and from accumulated experience. One of them is this: if you want to make an otherwise ordinary scene amusing, add a pig. Why? Because pigs are funny. Why? Nobody knows - they just are.
Compare the ad above by H Miller with the one yesterday by Ben Prins.
If the lady in the Prins ad had been trying to corral a pig instead of some loose chickens, you know you would have smiled the minute you set eyes on it.
Another rule of picture-making: The only thing funnier than just a pig in a scene is someone falling down in a pig sty. Why? You know why.